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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2016-11-27 00:13:34 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-12-02 00:52:34 +0100 |
| commit | b32614c03413f8a6025d8677c2b7c0ee976e63d4 (patch) | |
| tree | 31033ddc3ce2320c4f4faec012b7bfec6199b550 /kernel/trace/trace.c | |
| parent | oprofile/nmi timer: Convert to hotplug state machine (diff) | |
| download | linux-b32614c03413f8a6025d8677c2b7c0ee976e63d4.tar.xz linux-b32614c03413f8a6025d8677c2b7c0ee976e63d4.zip | |
tracing/rb: Convert to hotplug state machine
Install the callbacks via the state machine. The notifier in struct
ring_buffer is replaced by the multi instance interface. Upon
__ring_buffer_alloc() invocation, cpuhp_state_add_instance() will invoke
the trace_rb_cpu_prepare() on each CPU.
This callback may now fail. This means __ring_buffer_alloc() will fail and
cleanup (like previously) and during a CPU up event this failure will not
allow the CPU to come up.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161126231350.10321-7-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8696ce6bf2f6..465d56febc5b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7659,10 +7659,21 @@ __init static int tracer_alloc_buffers(void) raw_spin_lock_init(&global_trace.start_lock); + /* + * The prepare callbacks allocates some memory for the ring buffer. We + * don't free the buffer if the if the CPU goes down. If we were to free + * the buffer, then the user would lose any trace that was in the + * buffer. The memory will be removed once the "instance" is removed. + */ + ret = cpuhp_setup_state_multi(CPUHP_TRACE_RB_PREPARE, + "trace/RB:preapre", trace_rb_cpu_prepare, + NULL); + if (ret < 0) + goto out_free_cpumask; /* Used for event triggers */ temp_buffer = ring_buffer_alloc(PAGE_SIZE, RB_FL_OVERWRITE); if (!temp_buffer) - goto out_free_cpumask; + goto out_rm_hp_state; if (trace_create_savedcmd() < 0) goto out_free_temp_buffer; @@ -7723,6 +7734,8 @@ out_free_savedcmd: free_saved_cmdlines_buffer(savedcmd); out_free_temp_buffer: ring_buffer_free(temp_buffer); +out_rm_hp_state: + cpuhp_remove_multi_state(CPUHP_TRACE_RB_PREPARE); out_free_cpumask: free_cpumask_var(global_trace.tracing_cpumask); out_free_buffer_mask: |